The evolution of a Late Cretaceous–Cenozoic intraplate basin (Duaringa Basin), eastern Australia: evidence for the negative inversion of a pre-existing fold–thrust belt

International Journal of Earth Sciences - The Duaringa Basin in eastern Australia is a Late Cretaceous?–early Cenozoic sedimentary basin that developed simultaneously with the opening of the...     

Stable isotope characterization of pedogenic and lacustrine carbonates from the Chinese Tian Shan: Constraints on the Mesozoic–Lower Cenozoic palaeoenvironmental evolution

In the Mesozoic–Cenozoic continental deposits of the Tian Shan area, two main levels containing pedogenic carbonates have been identified on both the southern and northern foothills of the range: one in the Upper Jurassic series and one in the Upper Cretaceous–Lower Palaeocene series. In order to reconstruct the palaeoenvironmental and palaeotopographic characteristics of the Tian Shan area during these two periods, we measured the oxygen and carbon isotope composition of these pedogenic carbonates (calcrete and nodules). The stable isotope compositions are homogeneous: most δ¹⁸O values are between 21 and 25‰ and most δ¹³C values are between −4 and −6‰. No distinction can be made between the calcrete and nodule isotopic compositions. The constancy of isotopic values across the Tian Shan is evidence of a development of these calcification features in similar palaeoenvironmental conditions. The main inference is that no significant relief existed in that area at the Cretaceous−Palaeogene boundary, implying that most of the present relief developed later, during the Cenozoic. In addition to the pedogenic carbonates, few beds of limestones interstratified in the Jurassic series of the southern foothills display oxygen and carbon isotope compositions typical of lacustrine carbonates, ruling out brackish water incursion at that period in the region.     

Cenozoic paleo-environmental evolution of the Pamir–Tien Shan convergence zone

The retreat of the Tethys Sea and the uplift of the Tibetan Plateau play the critical roles in driving Asian climatic changes during the Cenozoic. In the Pamir–Tien Shan convergence zone, over 3000 m of Cenozoic successions, consisting of marine deposits in the lower, continental clay and fine sand in the middle, and molasse in the upper part, record the evolution of the Tethys Sea, the Asian aridification, and the deformation of the Pamir. In this work, the existing biostratigraphic subdivisions and new electronic spinning resonance dating results were used to assign ages to formations within the Ulugqat section. Sedimentary facies analysis and multi-proxy indices were used to reconstruct the paleo-environmental evolution. The results show: (1) the Pamir–Tien Shan convergence zone has undergone progressive environmental changes from shallow marine before ∼34 Ma to arid land at ∼23 Ma and finally to inter-mountain basin by ∼5.3 Ma; (2) the overall increase in mean size of grains, decrease in redness, in magnetic susceptibility, and in proportion of the ultrafine component of the sediments studied revealed a long-term strengthening in potential energy to transporting medium, cooling, and enhanced continental aridity, respectively; (3) the easternmost edge of the Tethys Sea prevailed in the western Tarim Basin from late Cretaceous to early Cenozoic, and finally retreated from this region around the Eocene–Oligocene transition, which in turn strengthened the Asian aridification; (4) accumulation of molasse with an upper age of ∼1 Ma suggests that the deformation front of the Pamir migrated to this area at or before that time.     

The age and geochemistry of volcanic rocks on the eastern flank of the Umlekan–Ogodzha volcanoplutonic belt (Amur region)

⁴⁰Ar/³⁹Ar dating yielded the reliable ages of andesite from the Unerikan complex (102.1 ± 1.4 Ma) and basaltic andesite from the Burunda complex (107.3 ± 2.4 Ma). The established age of volcanism is close to one of the stages of formation of the Khingan–Okhotsk volcanoplutonic belt. The petrography and geochemistry of basic, normal-basic, and normal rocks point to their dual character: They combine features specific for tholeiitic and calc-alkalic rocks. Most likely, these rocks formed in the setting of transform continental margin.     

Biostratigraphy of the Tethyan cretaceous successions from northwestern Zagros fold–thrust belt,Kurdistan region,NE Iraq

Nineteen benthonic and planktonic foraminiferal zones and their subzones have been recognized in the Tethyan cretaceous successions along the four sections analyzed in the northwestern Zagros fold–thrust belt within the preforeland–foreland basin. A detailed micropaleontological investigation revealed eight benthonic zones from the Qamchuqa Formation (Barremian to Lower Early Cenomanian) including: the Choffatella decipiens interval zone, C. decipiens/Palorbitolina lenticularis total range zone, C. decipiens/Salpingoporella dinarica interval zone, Mesorbitolina texana total range zone, Mesorbitolina subconcava total range zone, Orbitolina qatarica total range zone, Orbitolina sefini total range zone, and the Orbitolina concava partial range zone. The Rotalipora cushmani total range zone was recorded in the Dokan Formation that overlies the Qamchuqa Formation of the Late Cenomanian age. The Gulneri Formation is represented only by the Whitnella archaeocretacea partial range zone/Heterohelix moremani total range subzone and indicates the Late Cenomanian/Early Turonian age. Six planktonic foraminiferal zones were recorded from the Kometan Formation, indicating the Late Cenomanian to Early Campanian age, and are represented by the R. cushmani/H. moremani subzone, Helvetotruncana helvetica total range zone, Marginotruncana sigali partial range zone, Dicarinella primitiva interval range zone, Dicarinella concavata interval zone, Dicarinella assymetrica total range zone, and Globotruncanita elevata partial range zone. Two planktonic foraminferal zones were recorded also and these are related to the Globotruncana (fornicata, stuartiformis, elevata, and ventricosa) assemblage zone, Globotruncana calcarata total range subzone, from the Shiranish Formation, Lower Late Campanian, while the second zone is nominated as the Globotruncana (arca, tricarinata, esnehensis, and bahijae) assemblage zone, Globotruncana gansseri interval subzone, and Globotruncana contusa total range zone of the Late Campanian to basal middle Maastrichtian age. The last zone is related to the Abathomphalus mayaroensis partial range zone (of Late Maastrichtian age) and occasionally intercalated with the Orbitoides–Loftusia benthic zones. An important hiatus, between the Qamchuqa and Kometan formations was proved and manifests Pre-Aruma unconformity, and is occasionally associated with the global Cenomanian–Turonian Oceanic Anoxic Euxinic Event, while the Maastrichtian red bed of the Shiranish Formations mostly points to Tethyan upper Cretaceous Oceanic Red Bed.     

Reconstructing the Cryogenian–Ediacaran evolution of the Porongos fold and thrust belt,Southern Brasiliano Orogen,based on Zircon U–Pb–Hf–O isotopes

The Neoproterozoic geotectonic triad of the Brasiliano Orogen is reconstructed in southern Brazil from studies focused on the Porongos fold and thrust belt. We integrate field geology with isotopic studies of zircon U–Pb SHRIMP and Lu–Hf–O laser determinations in seven metasedimentary and three metavolcanic rock samples. The results indicate that the Porongos palaeo-basin was derived from mixed sources (3200–550 Ma), with major contributions from Rhyacian (2170 Ma) and Ediacaran (608 Ma) sources. Minor contributions from Archaean to Tonian sources are also registered. The maximum depositional age of the Porongos palaeo-basin is established by the age range of 650–550 Ma with T_DM model ages between 2.5 and 1.3 Ga. The reworked signature (ε_Hf values = ?34 to ?4) and the characteristic crustal magma reservoirs (δ¹⁸O ≥5.3 ‰) indicate that these sediments are equivalent to Neoproterozoic granites of the Dom Feliciano Belt. The episodic depositional history started in the Cryogenian (650 Ma) and lasted until the Ediacaran (most likely 570 Ma). A magmatic event of Tonian age is recorded in rhyodacite samples interleaved with the metasedimentary rocks and dated at 773, 801, and 809 Ma. The crustal evolution of the Sul-Riograndense Shield included mountain building, folding and thrusting and flexural subsidence in the foreland. An orogenic triad is revealed as the Pelotas Batholith, the Porongos fold and thrust belt and the Camaquã Basin, all part of the Dom Feliciano Belt.     

Structures and morphotectonic evolution of the frontal fold–thrust belt,Kameng river section,Arunachal Himalaya,India

The Neogene–Quaternary Siwalik foreland fold and thrust belt is studied for better understanding of tectonics along the Kameng river section of Arunachal Pradesh, India. The Kimi, Dafla, Subansiri, and the Kimin Formation correspond to Lower, Middle and Upper Siwaliks, respectively. The lithology in the foreland basin is dominantly sandstones, siltstones, claystones, carbonaceous shales, and boulder beds in the upper part. The structural style of the sedimentary sequence from the Main Boundary Thrust southward shows first order ramp-flat geometry. The brittle shear transfers slip across glide horizons to shallower depth. Repeated splay generations from a major regional-scale floor transfers slip from one glide horizon to another that shortens and thickens the crust. In the micro-scale, the lithological response in the structural development is well documented as pressure solution seams and other diagenetic deformation signatures. The basement asperity plays a significant role as the moving thrust front produced a major lateral ramp. The differential movement of the mountain front on both sides of the ramp is decipherable. This is especially true at the western part of the SE flowing Kameng river. The tectonic evolution of the area initiated with slip along the MBT \(\sim \)11 Ma ago along with the deposition of the Siwalik sediments. With southward propagation of the mountain front, the foreland basin shifted towards S, produced splay thrusts from the Himalayan Frontal Thrust-1 (HFT-1), which has been uplifting the Kimin and the older terraces.     

First data on late vendian granitoid magmatism of the Northwestern Sayan–Yenisei accretionary belt

Late Vendian (540–550 Ma) U–Pb age was established for zircon from postcollisional granites of the Osinovsky Massif located among island-arc complexes of the Isakovka terrane in the northwestern Sayan–Yenisei accretionary belt. The granites were formed 150 Ma after the formation of the host island-arc complexes and 50–60 Ma after the beginning of their accretion to the Siberian Craton. These events mark the final stage of the Neoproterozoic history of the Yenisei Ridge related to the end of accretion of oceanic fragments and the beginning of the Caledonian Orogeny. The granites are subalkaline leucoractic Na–K rocks enriched in Rb, U, and Th. The petrogeochemical and Sm–Nd isotope data (T_Nd(DM)-2st = 1490–1650 Ma and ε_Nd(T) from–2.5 to–4.4) indicate that their source was highly differentiated continental crust of the SW margin of the Siberian Craton. Therefore, the host Late Riphean island-arc complexes were thrust over the craton margin for distance significantly exceeding the size of the Osinovsky Massif.     

Structural setting of the Apennine－Maghrebian thrust belt

The Apennine-Maghrebian fold-and-thrust belt devel-oped from the latest Cretaceous to Early Pleistocene at the subduction-collisional boundary between the Euro-pean and the westward-subducted Ionian and Adria plates. Large parts of the Mesozoic oceanic lithosphere were subducted during an Alpine phase from the Late Cretaceous to Middle Eocene. The chain developed through the deformation of major paleogeographic internal domains (tectono-sedimentary sequences of the Ligurian-Piedmont Ocean) and external domains (sedi-mentary sequences derived from the deformation of the continental Adria-African passive mareinL The continu-ity of the Apennine chain is abruptly interrupted in the Calabrian Arc by the extensive klippe of Kabylo-Calabrian crystalline exotic terranes, derived from deformation of the European passive margin.Major complexities (sharp deflections in the arcuate configuration of the thrust belt, out-of-sequence propagation of the thrusts) are referred to contrasting rheology and differential buoyancy of the subducted lithosphere (transitional from conti-nental to oceanic) and consequent differential roll-back of the Adria plate margin, and to competence contrasts in the Mesozoic stratigraphic sequences,where multiple décollement horizons at different stratigraphic levels may have favored significant differential shortening.From the Late Miocene, the geometry of the thrust belt was strongly modified by extensional fault-ing, volcanic activity, crustal thinning and formation of oceanic crust correlated with the development of the Tyrrhenian Basin.     

The Chaqupacha Mississippi Valley-type Pb–Zn deposit,central Tibet: Ore formation in a fold and thrust belt of the India–Asia continental collision zone

The newly discovered Chaqupacha Mississippi Valley-type (MVT) Pb–Zn deposit in central Tibet has been found to be helpful for understanding MVT ore formation relative to tectonic evolution of a foreland fold and thrust belt. The deposit lies in the Tuotuohe area of the western Fenghuo Shan-Nangqian fold and thrust belt of the India–Asia continental collision zone. It contains NNW-striking and folded Late Permian strata including an upper clastic unit and an underlying limestone unit. The strata overlie late Oligocene clastic rocks through a south-dipping reverse fault that is associated with regional northward thrusting during the Paleogene. The Late Permian and late Oligocene strata are unconformably overlain by flat-lying early Miocene marl and mudstone of the Wudaoliang Formation. Lead and zinc ores are mainly hosted by pre-ore dissolution and collapse breccias in the Late Permian limestone. The style of mineralization is epigenetic, as shown by replacement of the pre-ore dissolution breccia matrix and open-space-fill by galena, sphalerite, calcite, and minor barite and pyrite. δ³⁴S values of the main sulfide galena range from − 27.5‰ to + 12.6‰. These features, together with the lack of magmatic activity during the mineralization, suggest that Chaqupacha is an MVT deposit. Subordinate mineralization is also present in the early Miocene Wudaoliang Formation marl and the paleokarst breccia which contains matrix compositionally equivalent to strata of the Wudaoliang Formation. The mineralization shares similar mineral associations and textures with the pre-ore dissolution breccia-hosted mineralization. Thus, the Pb and Zn mineralization in the entire deposit probably resulted from the same mineralizing event, which is younger than the youngest ore-hosting rocks (i.e., the early Miocene Wudaoliang Formation). Considering that thrusting in the Tuotuohe area had ceased prior to deposition of the Wudaoliang Formation host rocks, the mineralization at Chaqupacha post-dated the regional deformation. The Chaqupacha deposit thus provides a good example of MVT mineralization in a foreland fold and thrust belt that post-dates regional thrusting.     

The late Mesozoic–Cenozoic tectonic evolution of the South China Sea: A petrologic perspective

This paper presents a review of available petrological, geochonological and geochemical data for late Mesozoic to Recent igneous rocks in the South China Sea (SCS) and adjacent regions and a discussion of their petrogeneses and tectonic implications. The integration of these data with available geophysical and other geologic information led to the following tectono-magmatic model for the evolution of the SCS region. The geochemical characteristics of late Mesozoic granitic rocks in the Pearl River Mouth Basin (PRMB), micro-blocks in the SCS, the offshore continental shelf and Dalat zone in southern Vietnam, and the Schwaner Mountains in West Kalimantan, Borneo indicate that these are mainly I-type granites plus a small amount of S-type granites in the PRMB. These granitoids were formed in a continental arc tectonic setting, consistent with the ideas proposed by Holloway (1982) and Taylor and Hayes, 1980, Taylor and Hayes, 1983, that there existed an Andean-type volcanic arc during later Mesozoic era in the SCS region. The geochonological and geochemical characteristics of the volcanics indicate an early period of bimodal volcanism (60–43 Ma or 32 Ma) at the northern margin of the SCS, followed by a period of relatively passive style volcanism during Cenozoic seafloor spreading (37 or 30–16 Ma) within the SCS, and post-spreading volcanism (tholeiitic series at 17–8 Ma, followed by alkali series from 8 Ma to present) in the entire SCS region. The geodynamic setting of the earlier volcanics was an extensional regime, which resulted from the collision between India and Eurasian plates since the earliest Cenozoic, and that of the post-spreading volcanics may be related to mantle plume magmatism in Hainan Island. In addition, the nascent Hainan plume may have played a significant role in the extension along the northern margin and seafloor spreading in the SCS.     

Exhumation of the Neuquén Basin in the southern Central Andes (Malargüe fold and thrust belt) from field data and low-temperature thermochronology

Apatite fission-track analysis performed on eighteen Mesozoic sediment samples of the Neuquén Basin from the Southern Central Andes orogenic front between 35°30′ and 37°S has revealed Campanian-Paleocene (75-55 Ma), late Eocene-early Oligocene (35-30 Ma) and middle Miocene (15-10 Ma) cooling episodes. Each cooling episode corresponds closely with major unconformities observed in the preserved sedimentary sequences, and is associated with kilometer-scale additional burial and subsequent exhumation. A similar degree of cooling is inferred from associated vitrinite reflectance data. Late Eocene-early Oligocene exhumation is recognized only near the eastern orogenic front adjacent to the foreland in the southernmost part of the study area and may be related partly to within-plate magmatism and associated extension in the Palaoco Basin. The Campanian-Paleocene and middle Miocene cooling episodes are recognized more widely in the fold and thrust belt and appear to coincide with periods of eastward arc expansion and mountain building processes.     

Thin-skinned thrust mineralization in the Brasília fold belt: the example of the old Luziânia gold deposit

The Luziânia gold deposits in southern Goiás lie within the Late Proterozoic Brasília fold belt. The rocks that host the gold mineralization are a monotonous series of hydrothermally altered phyllites that have been subject to low grade regional metamorphism. The major controls on the gold mineralization are northeast trending and gently northwest dipping ductile-brittle, dextral-reverse shear zones associated with regional thin-skinned thrusting of the Canastra Group. From a preliminary fluid inclusion study it is deduced that low salinity, 7 eq. wt% NaCl, moderately dense, H₂O-CO₂ ± CH₄ ore fluids deposited gold at temperatures of 300 ± 75°C and pressures of 1.5 to 3 kb in the filling stage of the vein formation. Post-filling stage gold deposition probably occured by mixing of fluids at higher crustal levels (1.5–2 kb). During thrusting, prograde metamorphism released pore water which penetrated along thrust planes that acted as high permeability zones for the ponding and release, by hydraulic fracturing, of overpressured fluids. Later in the tectonic evolution and at shallower crustal levels, there was likely an incursion of near suface water into the fault zone.     

The Thakkhola–Mustang graben in Nepal and the late Cenozoic extension in the Higher Himalayas

The Thakkhola–Mustang graben is located at the northern side of the Dhaulagiri and Annapurna ranges in North Central Nepal. The structural pattern is mainly characterised by the N020–040° Thakkhola Fault system responsible for the development of the half-graben. A detailed study of the substrate and the sedimentary fill in several outcrops indicates polyphased faulting:-pre-sedimentation faulting (Miocene), with a mainly NNW–SSE to N–S compressional stress expressed in the substratum by N020–040° and N180–N010° sinistral and N130–140° dextral conjugate strike-slip faults;-syn-sedimentation faulting (Pliocene–Pleistocene), characterised by a W–E to WNW–ESE extensional stress and tectonic subsidence of the half-graben during the Tetang period (Pliocene probably), followed by a doming of the Tetang deposits and a short period of erosion (cf. Pliocene planation surface and unconformity between the Tetang and Thakkhola Formations); the Thakkhola period (Pleistocene) is characterized by a W–E to WNW–ESE extensional stress and a major subsidence of the half graben;-post-sedimentation recurrent extensional faulting and N–S and NE–SW normal faults in the late Quaternary terrace formations.Geodynamic interpretation of the faulting is discussed in relation to the following:

• 1.the geographic situation of the Thakkhola–Mustang half-graben in the southern part of Tibet and its setting in the Tethyan series above the South Tibetan Detachment System (STDS);
• 2.the geodynamic conditions of the convergence between India and Eurasia and the dextral east–west shearing between the High Himalayas and south Tibet;
• 3.the possible relations between the sinistral Thakkhola and the dextral Karakorum strike-slip faults in a N–S compressional stress regime during the Miocene.

     

Structural geometry of a thick‐skinned fold‐thrust belt termination: The Olary Block in the Adelaide Fold Belt,South Australia

The Olary Block comprises a set of Palaeoproterozoic to Mesoproterozoic basement inliers that were deformed together with the Neoproterozoic sedimentary cover of the Adelaide Geosyncline during the ca 500 Ma Cambro‐Ordovician Delamerian Orogeny. Balanced and restored structural sections across this region show shortening of less than 20%. These basement inliers represent the interface between a region of thick‐skinned deformation bordering the Curnamona Craton to the north and a region of thin‐skinned deformation to the south and west in the Nackara Arc. The basement inliers represent upthrust segments of the subsided basin margin with the sedimentary package thickening to the south and to the west. Earlier formed extensional faults provided the major strain guides during Delamerian shortening. An early phase of east‐west shortening is interpreted to be synchronous with dextral strike‐slip deformation along basement‐relay structures (e.g. Darling River lineament). During progressive shortening the tectonic transport direction rotated into a northwest to north direction, coeval with the onset of the main phase of thin‐skinned fold deformation in the adjacent Nackara Arc.     

New data on the evolution of the Tan–Lu fault belt: constraints from geological–geophysical surveys in the southern segment

The Tan–Lu fault is a well-known active fault belt in eastern China that has been the focus of geologic studies over the past 40 years. Since the late 1990s, numerous geophysical and geological investigations of this dislocation zone have been carried out by Chinese oil companies, as well as by universities. However, its deep structure, active periods of slip, and fault mechanism remain obscure. This study focuses on the deep structures within the Jiashan–Lujiang segment of the Tan–Lu fault belt, using high-precision geophysical tools, including magnetotelluric and magnetic sounding, and artificial seismic exploration using active source methods. Our results suggest that this segment is composed of several sub-faults. The southern part of the Tan–Lu fault belt, along the Jiashan–Lujiang sub-fault, can be divided into two parts on the basis of contrasting geological features. The Chihe–Taihu sub-fault is taken as the boundary between the two. The region east of the Chihe–Taihu sub-fault is dominated by strike–slip activity along several sub-faults. Only the Jiashan–Lujiang sub-fault is exposed at the surface, forming a large, positive flower structure, the result of late Middle Jurassic to early Late Jurassic strike–slip movement along the dislocation zone. Three sub-faults are present in Dingyuan County, two of which disappear in the southern Hefei Basin. Only the Chihe–Taihu sub-fault extends to the eastern edge of this basin, creating a half-graben depression that formed during the Early Cretaceous. Our results indicate that the present-day deep structure of the southern portion of the Tan–Lu fault zone is the result of a combination of strike–slip and extensional tectonics.     

Rainfall-induced landslide in the active frontal fold–thrust belt of Northwestern Himalaya,Jammu: dynamics inferred by geological evidences and Ground Penetrating Radar

Landslides are the most established geological hazards in the frontal fold–thrust belt of Northwestern Himalaya comprising of Siwaliks and Murree strata. The continuous rainfall from 2 to 6 September, 2014 caused a massive landslide at village Sadal in Udhampur district of Jammu and Kashmir state. The landslide occurred in the early morning of September 6, 2014, destroying entire Sadal habitation comprising 45 houses, and killing 41 people and more than 500 domestic animals. Google earth images of pre and post-landslide events along with the field measurements show the kinematics of upper and lower parts of the slide. Horizontal and vertical components of displacement and mode of failure suggest the landslide as of complex nature. The shallow subsurface geophysical imaging through Ground Penetrating Radar (GPR) survey shows the failure plane composed of friable mudstone bed underlain by massive mudstone and overlain by cross-bedded sandstone. The depth of debris material above the failure plane ranges from 6 m at Site S1a-b to 10 m at Site-S2b and 20 m at Site S3a. The velocity analysis of Site-3 shows four thick layers represented from bottom to surface by L1—sandstone (V?=?0.16 m/ns, travel time?=?356.36 ns), L2—mudstone (V?=?0.17 m/ns, travel time?=?288.48 ns), L3—massive mudstone (V?=?0.19 m/ns, travel time 220.68 ns), and L4—cross-laminated sandstone (V?=?0.20 m/ns, travel time?=?77.58 ns) overlaying the failure plane. The study shows the landslide occur along the western limb of a fold identified during the present work. We mapped an old landslide on the same limb which shows 5–6 m-thick subsurface debris material with thick rock fragments involved in the landslide process. The detailed geological and geophysical investigations suggest that both the landslides were triggered by extreme rain fall events.     

Geochemical and Sm–Nd isotope–geochemical patterns of metavolcanic rocks,diabase, and metagabbroids on the northeastern flank of the South Mongolian–Khingan orogenic belt

The first results of geochemical and Sm–Nd isotope–geochemical studies of metavolcanic rocks, metagabbroids, and diabase of the Nora-Sukhotino terrane, the least studied part of the South Mongolian–Khingan orogenic belt in the system of the Central Asian orogenic belt are reported. It is established that the basic rocks composing this terrane include varieties comparable with E-MORB, tholeiitic, and calc-alkaline basalt of island arc, calc-alkaline gabbro-diabase, and gabbroids of island arcs. Most likely, these formations should be correlated with metabasalt and associated Late Ordovician gabbro-amphibolite of the Sukdulkin “block” of the South Mongolian–Khingan orogenic belt, which are similar to tholeiite of intraplate island arcs by their geochemical characteristics.